Despite a harrowing youth -- a father killed by poachers, a sister murdered by a rival gorilla and a mother vanished -- the 400-pound silverback gorilla Titus ascends to the rank of the gorilla king, ruling over 25 of his fellow species. Now at age 33, Titus ponders his future in this enthralling "Nature" episode, which features amazing archival footage and observations from famed primatologist Dian Fossey and researcher Kelly Stewart.